#### Important One Mark Test ( Neet Based )

12th Standard

Reg.No. :
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Physics

Time : 01:00:00 Hrs
Total Marks : 100
I. Choose The Best Answers :
100 x 1 = 100
1. the force between2 charges when they are separated by a certain distance is 'F"N.when they are placed in medium, the distance of separation is halved to get the same force.what is the relative permittivity of the medium?

(a)

2

(b)

4

(c)

6

(d)

5

2. the  workdone to move a unit charge between two points in an equipotential surfaace

(a)

zero

(b)

possitiively minimum value

(c)

negatively minimum value

(d)

maximum

3. the potential due to charge of $\mu$C at a point of distance 3 m is

(a)

162 kV

(b)

1 8 kV

(c)

2$\times \quad$10-15 V

(d)

4.5$\times \quad$1015 V

4. a divice not working with the principle of electrostatic induction is

(a)

Van de Graff generator

(b)

Microwave oven

(c)

a and b

(d)

lightning arrestor

5. the forced experiienced by a charge of 5 C placed at point in a field E=6 NC-1 is

(a)

11 N

(b)

1.2 N

(c)

30 N

(d)

0.83 N

6. the insulation property of air breaks at E=3$\times$106 volt per meter. the maximum charge that can be given to a sphere of diameter is approximately

(a)

2$\times$10-2

(b)

2$\times$10-3

(c)

2$\times$10-4

(d)

2$\times$10-5

7. Which one of the following is a non-polar molecule?

(a)

${ H }_{ 2 }O$

(b)

${ CO }_{ 2 }$

(c)

$HCl$

(d)

${ O }_{ 2 }$

8. Equivalent capacitance of two capacitors when connected in parallel is $8\mu F$ and when connected in series is$15/8\mu F$.Then the valves of the two capacitors are

(a)

$7\mu F$ and $1\mu F$

(b)

$6\mu F$ and $2\mu F$

(c)

$4\mu F$  and $4\mu F$

(d)

$​​5\mu F$ and $3\mu F$

9. Two identical metal spheres have charges $+15\mu C$ and $+25\mu C$ are separated by a distance.If the spheres are first brought into contact and then separated to the original distance, then the ratio of the new force between them to the previous force is

(a)

15:16

(b)

3:5

(c)

16:15

(d)

5:3

10. If the moment of an electric dipole is $1.2\times { 10 }^{ -9 }Cm$and the distance between the charges is 3mm then the charge of the dipole is

(a)

$3.6\quad \mu C$

(b)

$40\quad \mu C$

(c)

$\quad 3.6\times { 10 }^{ -12 }C$

(d)

$0.4\quad \mu C\quad$

11. A parallel plate capacitor connected to a 12V source is charged to $21\quad \mu C$ If the capacitor is filled with an oil of dielectric constant 3, then the charge stored is

(a)

$7\quad \mu C$

(b)

$63\quad \mu C$

(c)

$​​14\quad \mu C$

(d)

$57\mu C$

12. The unit of electrochemical equivalent

(a)

$C kg^{-1}$

(b)

$kg C^{-1}$

(c)

C kg

(d)

$C^{-1} kg^{-1}$

13. In a carbon resistor it consists of yellow ,yellow and back rings at one end silver ring at the other end ,resistance is

(a)

$44000\pm 10\%\Omega$

(b)

$440\pm 10\%\Omega$

(c)

$44\pm 10\%\Omega$

(d)

$4400\pm 10\%\Omega$

14. The effective value of the resistances 6 ohm and 4 ohm when connected in parallel is

(a)

$10\Omega$

(b)

$1.5\Omega$

(c)

$2.4\Omega$

(d)

$0.66\Omega$

15. which of the following is Scalar ?

(a)

Current density

(b)

drift velocity

(c)

current

(d)

electric field

16. Drift velocity of electrons is of the order of

(a)

0.2 cm $s^{-1}$

(b)

0.1 cm $s^{-1}$

(c)

0.1 m$s^{-1}$

(d)

1 cm $s^{-1}$

17. What is the value of X for the balance of the Wheatstone's network given?

(a)

$42\Omega$

(b)

$32\Omega$

(c)

$22\Omega$

(d)

$0.022\Omega$

18. The resistance of a conductor of unit length having unit area of cross section is

(a)

resistivity

(b)

conductivity

(c)

conductance

(d)

capacitance

19. Drift velocity of electrons is proportional to

(a)

electric field intensity

(b)

charge of protons

(c)

area of the conductor

(d)

none of these

20. If the resistivity of materials ranges from 108-1014 $\Omega$m, then they are called as

(a)

insulators

(b)

conductors

(c)

semiconductors

(d)

none of these

21. Due to ageing, the internal resistance of a cell

(a)

increases

(b)

decreases

(c)

does not change

(d)

becomes zero

22. The ratio of the diameters of two copper wires of lengths 2m and 8m having equal resistance is

(a)

2:1

(b)

2:8

(c)

1:4

(d)

1:2

23. The galvanometer constant is given by

(a)

$K=\frac { n }{ ABC }$

(b)

$K=\frac { B }{ nCA }$

(c)

$K=\frac { A }{ nBC }$

(d)

$K=\frac { C }{ nBA }$

24. In an ammeter the amount of current flowing through low resistance is given by

(a)

${ I }_{ s }=I\quad \left( \frac { { I }_{ g } }{ S+G } \right)$

(b)

${ I }_{ s }=I_{ g }\quad \left( \frac { G }{ S+G } \right)$

(c)

${ I }_{ s }=G\quad \left( \frac { G }{ I+I_{ g } } \right)$

(d)

${ \quad \quad I }_{ s }=I\quad \left( \frac { G }{ S+G } \right)$

25. The resistance of the filament of a 60 W, 220 V electric bulb is

(a)

4 K$\Omega$

(b)

960 $\Omega$

(c)

250 $\Omega$

(d)

1440 $\Omega$

26. A conductor of length 50 cm is placed perpendicular ina uniform magnetic field. When 5 A current flows through it, the force acting on the conductor is 5x10-3 N, then find the value of magnetic field.

(a)

10x10-3 T

(b)

4x10-3 T

(c)

2x10-3 T

(d)

6x10-3 T

27. For a solenoid, whose length is very large compared to its radis, the magnetic field at points outside the solenoid is

(a)

maximum

(b)

minimum

(c)

zero

(d)

I/${ \mu }_{ o }$

28. How many 100 W bulbs may be safely used on 220 V with 5 A fuse?

(a)

22

(b)

11

(c)

10

(d)

20

29. By passsing a current in the coil, the magneticfiled produced at the centre is 22T. If aniron rodis inserted in the coil, the magnetic field is

(a)

< 22 T

(b)

> 22 T

(c)

= 22 T

(d)

Zero

30. A coil galvanometer consists of1 00 turns and effective area 1sq-cm. The restoring couple is 10-8 Nm/radian. The magnetic field between poles is 5 T. The current sensitivity of galvanometer is

(a)

5x104 radian/$\mu A$

(b)

5 radian/$\mu A$

(c)

5x10-7 A-1

(d)

5x10-6 A-1

31. _________ is used as one of the metal to form a thermocouple with another metal for the purpose of drawing thermoelectric diagrams.

(a)

Pt

(b)

Ag

(c)

Pb

(d)

Cu

32. _____ is a device used to detect thermal radiation

(a)

thermocouple

(b)

thermopile

(c)

thermometer

(d)

thermoscope

33. A current of 2A flows through 5 turn coil of a tangent galvanometer having a radius of 12.5 cm.If the deflection of the needle at the centre is $45°$ , the horizontal component of the earth field at that point is

(a)

$16\pi \times { 10 }^{ -5 }T$

(b)

$16\pi \times { 10 }^{ -6 }T$

(c)

$16\pi \times { 10 }^{ -7 }T$

(d)

$16\pi \times { 10 }^{ -8 }T$

34. The soft iron core in the a.c generator is used to

(a)

a)support the coil

(b)

b)increase the magnetic flux

(c)

c)both(a) and (b) are wrong

(d)

d)both(a) and (b) are correct

35. The reactance offered by an inductor to a DC is

(a)

${ X }_{ L }=\alpha$

(b)

${ X }_{ L }=0$

(c)

${ X }_{ L }=1$

(d)

${ X }_{ L }=L\omega$

36. Astep up transformer converts 220V into 1100V. If its output power is 1650 W then the value the input current is

(a)

1.5A

(b)

.15A

(c)

7.5A

(d)

0.75A

37. Unit of inductive reactance is

(a)

mho

(b)

mho m-1

(c)

ohm

(d)

ohm/metre

38. The emf in an A.C containing only inductance will

(a)

lags behind the current${ \pi }/{ 2 }$

(b)

be in phase with the current

(c)

be ahead of current by${ \pi }/{ 2 }$

(d)

always lag

39. Choke coils are commonly seen in

(a)

incandecent bulbs

(b)

flurecent tubes

(c)

stabilizer circuits

(d)

ratio

40. A transformeris used to light 140 W, 60 V lamp from 250 va.c mains.The current in the main cable is 0.6 A.The efficiency  of the transformer is

(a)

82.44%

(b)

44.44%

(c)

93.33%

(d)

63.33%

41. When in inductor is connected to an a.c circuit in series, the reactance of the circuit is

(a)

increased

(b)

unchanged

(c)

decreased

(d)

zero

42. In an LCR circuit with impedance of 5 $\Omega$ if the reactance is 3$\Omega$ the resistance should be

(a)

2$\Omega$

(b)

$4\Omega$

(c)

$6\Omega$

(d)

$8\Omega$

43. If an emf of 25V is induced when the current in the coil changes at the rate of 100 As-1 then the coefficient of self induction of the coil is

(a)

0.3 H

(b)

0.25 H

(c)

2.5 H

(d)

0.25 mH

44. The condition for  getting dark due to  intereference on thin films

(a)

${ X }_{ n }=(2n+1)D\lambda /d$

(b)

$2\mu t\quad cos\quad r=n\lambda$

(c)

$2\mu t\quad cos\quad r=(2n-1)\lambda /2$

(d)

$\\ { X }_{ n }=Dn\lambda /d$

45. In the pile of Plate instruments the glass plates are inclined at an angle ..................to the axis of the instrument

(a)

32o 5'

(b)

57.5o

(c)

52.5o

(d)

32o 30'

46. In a plane transmission grating the width of slit is 300 nm and width of line is 200nm , then 'N' value of grating is

(a)

6 x 105 Line/meter

(b)

2 x 106 Line/meter

(c)

1.5 x 109 Line/meter

(d)

6.5 x 109 Line/meter

47. The wavelength of electromagnetic waves produced by Hertz is

(a)

6m

(b)

600m

(c)

0.6cm

(d)

5 x 107 m

48. Wave front undergoing diffraction in Fraunhofer's diffraction is

(a)

Plane

(b)

spherical

(c)

Cylindrical

(d)

either spherical or cylindrical

49. If vg,vx and vm are the speeds of gamma rays , X-rays and micro respectively in vacccum , then

(a)

Vg<Vx<Vm

(b)

Vg>Vx>Vm

(c)

Vg>Vx<Vm

(d)

Vg=Vx=Vm

50. The time taken by the light to travel a distance of 200 m in a medium of refractive index 1.5 is

(a)

2 x 10-8

(b)

10-6​​​​ s

(c)

10-8​​​​ s

(d)

3 x 108​​​​​​​ s

51. Which of the following is not an optically active material ?

(a)

Quartz

(b)

sugar crystals

(c)

Turpentine oil

(d)

calcium chloride

52. In a plane transmission grating experiment , the wavelength of lights is $1/ \sqrt2$ times of grating element used . The angle of diffraction for the first order maximum will be

(a)

30o

(b)

45o

(c)

60o

(d)

90o

53. If A denotes the amount of scattering, the wavelength of light is proportional

(a)

inversely to A4

(b)

directly to  A4

(c)

inversely to A1/4

(d)

directly to A1/4

54. Regarding to the draw backs of Sommerfeld's atom model which of the following statement is incorrent?

(a)

It could not explain the distribution and arrangment of electronics in atoms.

(b)

It was unable to explain the fine structure of spectral lines of hydrogen atom

(c)

it could not explain Zeemen effect and Stark effect.

(d)

It does not give any explanation for the intensities of spectral lines

55. Regarding to the characteristics of laser which one is wrong?

(a)

highly intense

(b)

easily diverged

(c)

it is monochromatic

(d)

it is coherent

56. In lattice spacing of $3\times { 10 }^{ -10 }\quad m$; we get constructive interference of 4th order with angle of diffraction ${ 30 }^{ \circ }$.  Find the path difference between the reflected rays.

(a)

6 nm

(b)

2 nm

(c)

0.3 nm

(d)

12 nm

57. The intensity X-rays depends on

(a)

aceelerating voltage appiled to the tube

(b)

nature of the target

(c)

nature of the gas inside the tube

(d)

current in the filament

58. The fact that crystal can act as three dimesional grating for X-ray diffraction was suggested by

(a)

W.L Bragg and W.H Bragg

(b)

Moseley

(c)

Roentgen and Coolidge

(d)

Laue

59. The Process of taking atoms from ground state to excited state is called

(a)

pumping

(b)

ionisation

(c)

excitation

(d)

stimulation

60. The ionisation potential of hydrogen atom is

(a)

13.6 eV

(b)

- 13.6 eV

(c)

13.6 eV

(d)

- 13.6 eV

61. According to Rutherford atom model, the spectral line emitted by an atom is ________spectrum

(a)

line

(b)

continuous spectrum

(c)

continuous absorption

(d)

band

62. The size of an atom from Rutherford experiment is________

(a)

10-10m

(b)

10-16m

(c)

10-14m

(d)

10-12m

63. The ratio of the specific charge of an electron to that of a proton is________

(a)

1:2

(b)

1:1

(c)

2:1

(d)

1:4

64. In classical mechanics , about the concept of space , the geometrical form of object is

(a)

changes in position

(b)

state of motion of the object

(c)

observer

(d)

irrespective to all the above

65. The phenomenon in which the photon behaves like a particle is

(a)

interference effect

(b)

diffraction effect

(c)

polarisation effect

(d)

emission of light

66. Newton's laws are not valid in

(a)

inertial frames

(b)

non - inertial frames

(c)

all frames

(d)

references frames

67. Which of the following is / are true about photons  ?

(a)

Reset mass of photon is zero

(b)

mass of photon is $h\upsilon\over c^{2}$

(c)

Linear momentum of photon is $h\upsilon\over c$

(d)

all these

68. The threshold frequency of a metal of work function 3.31 eV is

(a)

1.6 x 1015 Hz

(b)

3.2 x 1016 Hz

(c)

0.8 x 1015 Hz

(d)

2.4 x 1016 Hz

69. In inertial frame of reference , if no external force is acting , a particle continuous to be

(a)

at rest

(b)

at uniform motion

(c)

moving in all direction

(d)

either (a) or (b)

70. The wavelength ratio of proton and deuteron when they are accelerated by a same potential ' V '.

(a)

1 : 1

(b)

1 : 2

(c)

$\sqrt {2} : 1$

(d)

2 : 1

71. The energy equivalence of mass of 1 milligram is

(a)

9 x 1010 J

(b)

9 x 1013 J

(c)

9 x 1019 J

(d)

9 x 1016 J

72. If the momentum of a radiating photon is $3.3\times { 10 }^{ -29 }kg{ ms }^{ -1 }$ then its waveelngth is____

(a)

$6\times { 10 }^{ -3 }m$

(b)

$3\times { 10 }^{ -3 }m$

(c)

$2\times { 10 }^{ -3 }m$

(d)

$2\times { 10 }^{ -5 }m$

73. If threshold wavelength of sodium is $6800\mathring { A }$ what is its work function?

(a)

0.91eV

(b)

13.6 eV

(c)

1.82 eV

(d)

1.72 eV

74. Of the following, which is true about nuclear force?

(a)

Charge independent

(b)

Less than gravitational force

(c)

Long range

(d)

Repulsive

75. A radioactive substance has a half-life period of 30 days. The disintegration constant is

(a)

0.0231 day-1

(b)

0.231 day-1

(c)

2.31 day-1

(d)

23.1 day-1

76. The instrument used to measure the intensity of radioactive is

(a)

cyclotron

(b)

Bainbridge spectrometer

(c)

electron microscope

(d)

Geiger - Muller counter

77. Which of the following pair is isobar?

(a)

$_{ 1 }{ H }^{ 1 }_{ \quad ,\quad 1 }{ H }^{ 2 }$

(b)

$_{ 6 }{ C }^{ 14 }_{ ,\quad 8 }{ O }^{ 16 }$

(c)

$_{ 8 }{ O }^{ 16 },_{ 7 }{ N }^{ 16 }$

(d)

$_{ 6 }{ C }^{ 12 },_{ 6 }{ C }^{ 14 }$

78. Without changing chemical properties, the following particals can be added to the nucleus of an atom

(a)

protons

(b)

electrons

(c)

neutrons

(d)

both protons and  neutrons

79. If a radioactive element $_{ Z }{ X }^{ A }$decay by emitting an $\alpha$ -particle and a $\gamma$ photons,then the new element is

(a)

$_{ Z-4 }{ X }^{ A-Z }$

(b)

$_{ Z+2 }{ X }^{ A+4 }$

(c)

$_{ Z-2 }{ X }^{ A-4}$

(d)

$_{ Z+4}{ X }^{ A+2 }$

80. Which of the following particles is a leptons?

(a)

Electron

(b)

proton

(c)

Neutron

(d)

$\pi$ - Meson

81. According to the law of disnntegration $N=No\quad { e }^{ \lambda t }$,the number of radioactive atoms that have been decayed during a time of tis

(a)

N

(b)

N

(c)

N-N

(d)

$\frac { No }{ 2 }$

82. If 10% of a radioactive material decay in 5 days ,then amount of orginal material left after 20 days is approximately

(a)

60%

(b)

65%

(c)

70%

(d)

75%

83. Nuclear force is a ...............................

(a)

long range force

(b)

short range force

(c)

repulsive force

(d)

charge based force

84. The advantages of negative feed back is

(a)

less distortion

(b)

decreased bandwidth

(c)

low input impedence

(d)

all the above

85. A transistor has a collector current 10 mA and collector-emitter voltage 12V.  Then the output power dissipation is

(a)

1.2 mW

(b)

4.14 W

(c)

120 mW

(d)

9.4 W

86. If mid frequency gain+ 50 then gain of amplifier at upper cut off frequency region is

(a)

70.7

(b)

51.4

(c)

354

(d)

35.4

87. The current gain of a common base amplifier is

(a)

less than one

(b)

greater than one

(c)

between 50 and 300

(d)

zero

88. In mid frequency range of RC coupled amplifier, when the frequency of input signal increases, the voltage gain of the amplifier

(a)

also increased

(b)

is reduced to zero

(c)

decreases

(d)

remains constant

89. quiscent point of a transistor amplifier is the point of intersection of load line and output characteristics curve in

(a)

saturation region

(b)

cut off region

(c)

active region

(d)

either of these

90. When collector current and base current are respectively6.5 mA and 131$㎂$ , the current gain in CB mode is

(a)

49.6

(b)

0.02

(c)

98

(d)

0.98

91. The voltage gain of an amplifier is 140. When a negative feedback is applied the gain is reduced to 17.5. The feedback fraction is

(a)

$\frac { 1 }{ 10 }$

(b)

$\frac { 1 }{ 15 }$

(c)

$\frac { 1 }{ 5 }$

(d)

$\frac { 1 }{ 20 }$

92. During the normal operation of a transistor, if its base current is increased then its,

(a)

${ V }_{ CE }$ will increase

(b)

${ I }_{ c }$ will decrease

(c)

${ I }_{ c }$ will increase

(d)

${ V }_{ CC }$ will increase

93. Which layer of atmosphere absorbs large amount of radiant energies?

(a)

a)Chromosphere

(b)

b) Ionosphere

(c)

c)Troposphere

(d)

d) Exosphere

94. In Radar, to locate the direction of the target a ________ antenna is used

(a)

a) Directional

(b)

b) Half wave dipole

(c)

c) Sharp

(d)

d) Hertz

95. In twisted pair cable, the wire is twisted to minimize

(a)

a)The voltage

(b)

b) Power consumption

(c)

c) External noise

(d)

d) All the above

96. In radar, the transmitter is a high power ______ oscillator which generates high power pulses

(a)

colpitt

(b)

hartley

(c)

magnetron

(d)

klystron

97.  The ability to amplify the weak signals is known as

(a)

selectivity

(b)

sensitivity

(c)

fidelity

(d)

compatibility

98. Indicate which one of the following is not an advantage of FM  over AM

(a)

Better noise immunity is provided

(b)

Lower bandwidth is required

(c)

The transmitted power is more useful

(d)

Less modulating power is required

99. Skip distance is the shotest distance between

(a)

the point of transmission and the point of reception

(b)

(c)

the transmitter and the target

(d)

100. Receiving antenna converts the________

(a)

electrical signal into electromagnetic energy

(b)

electrical signal into electrical energy

(c)

electromagnetic energy into electrical signal

(d)

electromagnetic energy into magnetic signal